I can never remember how to mount a drive, let alone a LUKS-encrypted one.
Here’s how I do it on my Raspberry Pi with an external drive named Domino,
based on this Stack Exchange
post.
You can use df -h if you don’t know the drive number.
Decrypt & Open
sudo mkdir /media/pi/Domino
sudo cryptsetup luksOpen /dev/sda1 Domino
sudo mount /dev/mapper/Domino /media/pi/Domino
Close & Encrypt
sudo umount /media/pi/Domino
sudo cryptsetup luksClose Domino